An oxide catalyst for exhaust gas cleaning up for removing carbon monoxide, unburnt hydrocarbons, soluble organic fractions and soot discharged from internal combustion engines, in particular diesel engines, resistant to poisoning by sulfur, working in a reduced quantity, and causing sulfate emissions to a limited extent while treating exhaust gases of high temperature; an oxide catalyst of integral structure using the above oxide catalyst; and a method for cleaning up exhaust gases using the above oxide catalyst of integral structure. The oxide catalyst for exhaust gas cleaning up, comprising a silica/alumina-based base (B) which supports a noble metal, and zeolite; the oxide catalyst of integral structure, supporting the above catalyst on a carrier of integral structure; and the method which positions the above oxide catalyst of integral structure in an exhaust gas passage of diesel engine and allows the exhaust gases to pass therethrough.
